Apparatus for transporting and intermittently braking webs of paper or the like

ABSTRACT

Apparatus for intermittently moving a web of photographic film lengthwise has a driven roller which engages the underside of the web, a small idler roller which is normally biased against the upper side of the web opposite the driven roller, and a braking device having a cylindrical braking element movable by an electromagnet against the underside of the web to disengage the web from the driven roller, to move the idler roller away from the driven roller by way of the web, and to press the web against the idler roller to thus effect rapid stoppage of the web. The electromagnet is energized at predetermined intervals in response to detection of marks which are applied to a processed web at the same intervals as the frame lines between successive frames so that the frame lines can be cut in half during each stoppage of the web, or in response to signals from a metering device which measures the length of the web and causes the braking device to arrest the web whenever an unexposed frame of the web registers with the exposing station of a photographic copying machine.

limited States Patent Weinert et al.

[ Dec. 11, 1973 AGFA-Gevaert Aktiengesellschaft, Leverkusen, Germany Filed: Sept. 28, 1971 Appl. No.: 184,498

Assignee:

[30] Foreign Application Priority Data Oct. 2, 1970 Germany P 20 48 413.3

US. Cl 226/33, 226/39, 226/154, 226/195 Int. Cl. B65h 23/06 Field of Search 226/33, 39, 48, 154, 226/155, 195

References Cited UNITED STATES PATENTS 3/1952 Williams 226/48 8/1959 Funnell 226/155 X 6/1967 Epstein 226/39 X 3,525,463 8/1970 Gerfast 226/154 X Primary ExaminerRichard A. Schacher Attorney-Michael S. Striker [57] ABSTRACT Apparatus for intermittently moving a web of photographic film lengthwise has a driven roller which engages the underside of the web, a small idler roller which is normally biased against the upper side of the web opposite the driven roller, and a braking device having a cylindrical braking element movable by an electromagnet against the underside of the web to disengage the web from the driven roller, to move the idler roller away from the driven roller by way of the web, and to press the web against the idler roller to thus effect rapid stoppage of the web. The electromagnet is energized at predetermined intervals in response to detection of marks which are applied to a processed web at the same intervals as the frame lines between successive frames so that the frame lines can be cut in half during each stoppage of the web, or in response to signals from a metering device which measures the length of the web and causes the braking device to arrest the web whenever an unexposed frame of the web registers with the exposing station of a photographic copying machine.

23 Claims, 3 Drawing Figures PAIENIEB DEC] 1 ma snm1nr INVENTOP 5' VOLKER WEINERT GERHARD FRANKIEWICZ BY GUNTER ENGELAGE 7Z1 F Z/ [1 PATENTED N 1 sum 2 er 3- INVENTORS VOLKER WEINERT egRHARD FRANKIEWICZ BY GUNTER ENGELAGE PMENIEB am 11973 sum: or 3 INVENTORE VOLKER WEINERT GERHARD FRANKIEWlCZ BY GUNTER ENGELAGE APPARATUS FOR TRANSPORTING AND INTERMITTENTLY BRAKING WEBS OF PAPER OR THE LIKE BACKGROUND OF THE INVENTION The present invention relates to apparatus for transporting and braking webs of paper or the like, particularly for transporting and intermittently braking webs of processed or unprocessed photographic film. Such apparatus can be utilized for intermittent transport of processed film in order to place successive frame lines into registry with the knife or knives of a severing or cutting device or to place successive frames of a photo sensitive layer into register with the exposing station of a photographic copying machine.

It is known to provide a web of processed photographic film with indicia in the form of graphite marks which are detected by a suitable scanning device serving to arrest the drive for the web so that successive frame lines are moved into register with the cutter in response to successive stoppages of the web. It is also known to intermittently transport a web which is coated with a photosensitive layer through a printing station and to arrest the web at regular intervals during each of which a different portion of the photosensitive layer registers with the lens of the printing or copying machine so that it can be exposed to light.

The presently known apparatus for intermittent transport of webs of processed photographic film for the purpose of severing the film during each interval between successive lengthwise movements exhibit a number of drawbacks, especially as concerns the reproducibility of the braking action. The problem is further aggrevated if the web is to be transported at a high speed because of the reproducibility of the braking action decreases proportionally with increasing maximum forward speed of the web. Certain conventional transporting and braking apparatus employ an intermittently operated or reversible electric motor which must be arrested or reversed in order to produce a braking action. This means that the reproducibility of the braking action is dependent on the mass of the rotor of the electric motor as well as on the mass of one or more transmissions which are interposed between the rotor and with that part of those parts of the transporting apparatus which come into direct contact with the web. Rapid deceleration of such substantial masses necessitates the conversion of their kinetic energy into heat, normally by friction. This, in turn, affects the reproducibility of the braking action since the length of intervals which are required for braking depends on such unpredictable factors as the friction coefficient of various materials; therefore, the length of intervals which are required to complete successive braking actions fluctuates within a very wide range which is particularly undesir able when the web is to be severed during each period of dwell because the web is not cut exactly midway across the frame lines. Similar problems arise in connection with the operation of apparatus for intermittent transport of webs of unexposed photographic film through a photographic printing or copying machine; if the braking action is not reproducible with a high degree of accuracy, the width of frame lines between successively exposed areas of the film will fluctuate and this affects the appearance of the prints.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved apparatus for intermittent transport of webs of processed or unprocessed photographic film or other types of sheet stock which is capable of arresting the web at accurately determined intervals to insure highly statisfactory reproducibility of the braking action with attendant enhancement of the appearance of prints 0 which are obtained upon subdivision of such webs.

Another object of the invention is to provide an apparatus which can be readily adjusted to intermittently arrest the web at longer or shorter intervals.

A further object of the invention is to provide an apparatus which is particularly suited for intermittent transport of unexposed photographic film through a photographic copying machine and/or for intermittent transport of processed film through a severing station where the film is cut midway across the frame lines to yield discrete prints.

An additional object of the invention is to provide the above outlined apparatus with novel and improved web transporting and braking devices and to construct such devices with a view to insure rapid acceleration and equally rapid deceleration of the web.

A further object of the invention is to provide an apparatus wherein the mass of rotating parts has little or no influence on the reproducibility of the braking action and wherein the mass of those parts which must be decelerated during braking of the web is a very small fraction of the combined mass of corresponding parts in conventional apparatus.

The invention is embodied in an apparatus for manipulating webs of processed or unprocessed photographic film or the like and comprises a transporting device and a braking device. The transporting device includes a driven roller which is arranged to engage one side of a web and an idler roller which is located opposite the driven roller and is movable to and from an operative position of engagement with the other side of the web which is engaged by the driven roller to thereby cooperate with the driven roller in positively advancing the web lengthwise while it dwells in the operative position. The braking device includes a braking element and displacing means which is actuatable to move the braking element against the one side of the web to thus disengage the web from the driven roller to brake the web and to move the idler roller from the operative position. The braking element is preferably movable into engagement with the web opposite the idler roller and with a force which is sufficient to disengage the web from the driven roller, to move the idler roller from the operative position through the intermediary of the web, and to press the web against the idler roller while the latter is out of the operative position to thus effect rapid stoppage of the web.

The displacing device may comprise an electromagnet which is actuatable by a scanning device which serves to detect indicia provided on the web at the same intervals as the frame lines between successive film frames or by a scanning device which determines the length of those increments of web which advance past a portion of the path for the web and causes the braking device to stop the web whenever an unexposed portion of the web registers with the exposing station of a photographic printing or copying machine.

The braking element preferably engages the web along a line which is coplanar with the axis of the driven roller; such linear contact between the web and the braking element is maintained while the idler roller is out of its operative position. The masses of the braking element and idler roller are preferably very small in comparison to the mass of the driven roller.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of opera tion, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. 1 is a partly elevational and partly vertical sectional view of a first apparatus which is utilized for transporting and intermittently braking a paper web carrying a series of images and being about to be severed to yield discrete prints, the section being taken in the direction of arrows as seen from the line II of FIG. 2;

FIG. 2 is a sectional view substantially as seen in the direction of arrows from the line IIII of FIG. 1; and

FIG. 3 is a partly elevational and partly vertical sectional view of a second apparatus which is used to transport and to intermittently brake a photosensitive web through a photoprinting machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

Referring first to FIGS. 1 and 2, there is shown an apparatus which is utilized to transport, intermittently brake and sever a web 1 of processed photographic film, e.g., a paper web, the upper side of which carries a series of images separated from each other by frame lines, not shown. The web 1 is assumed to have been transported through a photographic printing apparatus wherein a photosensitive emulsion at one of its sides was exposed to scene light passing through a succession of transparent originals and thereupon through a developing apparatus, not shown. The purpose of the apparatus shown in FIGS. 1 and 2 is to transport the web 1 lengthwise in stepwise fashion and to intermittently brake and arrest the web whenever a frame line between a pair of successive images reaches a severing station 104 where the web is severed across the frame line so that it is subdivided into a series of discrete reproductions or prints. One side of the web 1 is provided with detectable indicia (not specifically shown) which are equidistant from each other and the distance between the centers of which equals the distance between the centers of successive frame lines at the upper side of the web 1. The indicia (e.g., marks applied to the underside or to the upper side of the web by a graphite wheel or the like) may but need not be in register with the frame lines, as long as their mutual spacing corresponds to that between the frame lines. The web 1 is scanned for marks by a scanning or detecting device 2 which may constitute or employ a photoelectric detector with a light source serving to direct against the marked side of the web 1 a beam of light and with a photosensitive receiver which is exposed to reflected light, or a detector which responds to changes in conductivity of the web in response to detection of a mark.

Such scanning devices are known in the art of apparatus for treating webs of paper or the like for the presence or absence of graphite marks or other indicia and, therefore, the exact construction of the scanning device 2 forms no part of the present invention.

The web 1 is transported lengthwise by a conveyor or transporting device 3 which includes means for engaging the web at opposite sides and for pulling it in the direction indicated by arrow 33. Due to the provision of a novel braking device, the transporting device 3 advances the web 1 stepwise so as to place successive frame lines at the upper side of the web into register with the knives 5, 5a of a severing or cutting device 4 of the station 104 whereby the device 4 severs the web at predetermined intervals to separate therefrom discrete prints. The movable knife 5 of the severing device 4 is caused to perform working strokes in response to signals from the scanning device 2.

The transporting device 3 comprises an electric motor 6 which is shown in FIG. 2 and has a horizontal output shaft 8 serving to drive a two-piece roller 7 of the transporting device. As a rule, the roller 7 will be driven through the intermediary of a suitable transmission and/or one or more flat belts or analogous torque transmitting means of known design. The motor 6 is preferably on as long as the apparatus is in use and drives the roller 7 at a constant speed. The shaft 8 is mounted in one or more antifriction bearings B installed in a housing H. The two mirror symmetrical portions or disks 7a, 7b of the roller 7 are driven at identical speeds and their peripheral surfaces are preferably coated with thin layers of friction generating elastic material, such as rubber. Each of the driven roller portions 70, 7b engages a different marginal portion of the web 1.

As best shown in FIG. 1, the driven roller 7 cooperates with a relatively small idler roller 9 which is mounted at a level above the path of the web 1 opposite the roller 7 and is movable up and down from and to an operative position. The idler roller 9 is journalled in the U-shaped portion or yoke 10a of a block 10 which is pivotable in a frame member F of the housing H about the axis of a horizontal shaft 11 extending transversely of and at a level above the path for the web 1. A helical spring 12'reacts against the frame member F and serves to bias the block 10 in a counterclockwise direction, as viewed in FIG. 1, so as to urge the idler roller 9 against the upper side of the web 1 whereby the latter moves lengthwise (arrow 33) at the peripheral speed of the portions 7a, 7b of the driven roller 7. The upper end convolution of the spring 12 reacts against the head of an adjusting screw 13 which meshes with the frame member F and is rotatable to thereby adjust the bias of the spring 12 and hence the force with which the idler roller 9 bears against the web 1.

The yoke 10a of the block 10 is provided with an inverted L-shaped bracket or extension 14 whose horizontal arm constitutes a follower for an eccentric cam 15 which is rotatable on a shaft 17 of the frame member F through the intennediary of an actuating member or lever 16 which is accessible at a level above the frame member F. By pivoting the lever 16 in a counterclockwise direction, as viewed in FIG. 1, the operator can pivot the block 10 about the axis of the shaft 11 to thereby lift the idler roller 9 above and away from contact with the web 1, Le, to move the roller 9 from its operative position. Such manual pivoting of the block and idler roller 9 will be carried out for the purpose of threading the leading end of a fresh web 1 into the space between the rollers 7 and 9 of the transporting device. The frame member F further supports two adjustable stops 18 which are provided with external threads to be movable up or down in response to their rotation and to determine the maximum extent of pivotal movement of the idler roller 9 against the opposition of the spring 12, either in response to manual pivoting of the lever 16 or in response to actuation of the braking device 3 which will be described below. The upper end portions of the stops 18 carry lock nuts 18a which prevent accidental changes in their axial positions. The maxium stroke of the block 10 in a clockwise direction, as viewed in FIG. 1, is selected in such a way that the yoke 10a abuts against the lower end portions of the stops 18 before a rotary electromagnet 30 of the braking device 3 completes its angular movement in response to completion of an electric circuit. The electromagnet 30 forms part of a displacing means which serves to lift the idler roller 9 above and away from the driven roller 7 in response to signals from the scanning device 2.

The braking device 3 further comprises a carrier or lifter 19 which has a bifurcated upper portion flanking the shaft 8 in the space between the portions 7a, 7b of the driven roller 7. The upper end portions of the prongs of the bifurcated upper portion of the carrier 19 are connected to each other by a horizontal bridge member 20 the central portion of which carries a substantially hemispherical motion transmitting element 21. The latter is in mere point contact with the underside of an elastic follower or holder 22 which is mounted on two resilient supporting elements here shown as leaf springs 23. These leaf springs are anchored in the housing H. In the illustrated embodiment, the leaf springs 23 are anchored in the counterknife 5a of the severing device 4 for the web 1. The leaf springs 23 insure that the holder 22 can be tilted with reference to the plane of the adjacent portion of the web 1 in at least two directions but has practically no freedom of movement laterally of the path for the web. The upper side of the holder 22 is provided with a socket 24 for a substantially rod-shaped braking element 25 of circular outline. The axis of the braking element 25 in undeformed condition of the leaf springs 23 is at least substantially parallel to the plane of the adjacent portion of the web 1. In its presently preferred form, the braking element 25 consists of a synthetic plastic material having a high resistance to wear and a high coefficient of friction. For example, the element 25 may consist of polyurethane having a proper degree of hardness.

The lower portion of the carrier 19 extends to a level below the driven roller 7 and is reciprocable in an upright guide sleeve 26 mounted in the housing H. This lower portion of the carrier 19 has a suitably configurated slot for a pin 27 which is mounted on a crank arm 28. The latter is clamped to a stub shaft 29 of the rotary armature of the electromagnet 30. The armature of the electromagnet 30 is rotatable in a bracket 31 of the housing H. A helical coupling spring 32 reacts against the housing H and bears against the crank arm 28; the purpose of this spring is to insure that the armature of the electromagnet 30 does not rotate the crank arm 28 beyond a certain angular position when the electromagnet 30 is deenergized. Such tendency of the armature (which rotates the crank arm 28 by way of the stub shaft 29) is due to the provision ofa spring (not shown) which biases the stub shaft 29 in a counterclockwise direction, as viewed in FIG. 1, so as to cause the carrier 19 to move downwardly and to maintain the braking element 25 out of contact with the underside of the web 1. The braking element 25 can engage the web at a point immediately below the lowermost point of the peripheral surface on the idler roller 9 in the space between the portions 7a, 7b of the driven roller 7. It will be noted that the coupling spring 32 counteracts the tendency of the deenergized electromagnet 30 to move the braking element 25 too far away from the underside of the web 1.

THE OPERATION Prior to starting the drive means 6 for the roller 7,.the operator pivots the lever 16 in a clockwise direction so as to raise the idler roller 9 above and away from the roller 7 through the intermediary of the cam 15 and follower 14 on the yoke 10a of the block 10. This provides between the roller 7 and 9 a gap for convenient threading of the leading end of a fresh web 1 which is introduced into such gap in the direction indicated by the arrow 33. The leading end is moved beyond such gap and into the space between the knives 5, 5a of the severing device 4. The lever 16 is then returned to its starting or idle position so that the spring 12 is free to bias the idler roller 9 against the upper side of the web 1 (and to thus bias the web against the portions 7a, 7b of the driven roller 7) with a force which is determined by the setting of the bias adjusting screw 13.

In the next step, the operator completes the circuit of the motor 6 so that the shaft 8 rotates the roller 7 and the roller 7 cooperates with the idler roller 9 to advance the web 1 lengthwise in the direction indicated by the arrow 33. When the scanning device 2 detects a frame line mark at the adjacent side of the travelling web 1, the braking device 3 is actuated by completing the circuit of the electromagnet 30 which rotates the crank arm 28 in a clockwise direction, as viewed in FIG. 1, whereby the pin 27 moves the carrier 19 upwardly and the motion transmitting element 21 on the bridge 20 bears against the underside of the holder 22. The latter lifts the socket 24 and the braking element 25 against the opposition of the leaf springs 23 (which normally maintain -the braking element 25 out of contact with the underside of the web 1) whereby the braking element 25 engages the underside of the web 1 and presses it against the idler roller 9. The idler roller 9 moves upwardly against the opposition of the spring 12 so that it cannot cooperate with the driven roller 7. The rotary electromagnet 30 can produce a substantial force and causes the braking element 25 to lift the roller 9 after elapse of a very short interval of time because the spring 32 insures that the crank arm 28 normally dwells in a position in which the braking element 25 is closely adjacent to but still spaced from the underside of the travelling web 1 between the portions 70, 7b of the driven roller 7.

It will be noted that the upward movement of the carrier 19 results in immediate disengagement of the web 1 from the driven roller 7 and also in the generation of a strong force which urges the braking element 25 against the underside of the web 1 whereby the upper side of the web is pressed against the peripheral surface of the idler roller 9. The pivotal movement of the block 10 for the idler roller 9 is terminated when the yoke a moves into abutment with the stops 18. The electromagnet 30 continues to urge the carrier 19 upwardly so that the pressure between the braking element 25 and the underside of the web 1 on the one hand and the pressure between the upper side of the web 1 and the peripheral surface of the idler roller 9 on the other hand either increases or remains unchanged to thus insure that the web 1 is brought to a full stop with a minimum of delay. In such angular position, the electromagnet 30 operates with a minimal gap. The braking action of the parts 9 and 25 upon the web 1 is highly satisfactory because the roller 9 is an idler roller and its mass is small so that the adjacent portions of the web 1 are neither scratched nor otherwise damaged or defaced in response to the application of a substantial braking force. The idler roller 9 engages the image bearing upper side of the web 1 and the braking element 25 engages the other or rear side of the web. The kinetic energy of the web 1 is negligible and the same holds true for the relatively small and lightweight idler roller 9 so that the deceleration of the web 1 to zero speed takes up a very short interval of time. It was found that the just described braking action is reproducible with a high degree of accuracy, i.e., that the web 1 is brought to a full stop after covering an accurately determined distance following the transmission of a signal by the scanning device 2, such signal being generated in response to detection of a frame line mark.

An advantage of the leaf springs 23 is that they allow the braking element 25 to move into exact parallelism with the axis of the idler roller 9 while its peripheral surface engages the underside of the web 1. Thus, and since the socket 24 for the braking element 25 is tiltable in several directions but is held against sidewise movement with reference to the path for the web 1, the braking force is applied uniformly all the way along the full axial length of the element 25 to thus further reduce the likelihood of damage or defacing of the web 1 as well as a practically instantaneous and accurately reproducible braking action. In the absence of springs 23, the carrier 19 of the displacing means 19, 30 would have to be guided and machined with a high degree of precision in order to insure the application of a uniform braking force all the way across that portion of the web 1 which extends between the portions 7a, 7b of the driven roller 7.

The combined mass of all parts which are moved in response to energization of the rotary electromagnet 30 is very small. This is desirable and advantageous because the electromagnet can respond to signals from the scanning device 2 with minimal delay and is capable of practically instantaneously lifting the braking element 25 into requisite frictional engagement with the underside of the web 1 as well as of simultaneously moving the idler roller 9 upwardly and away from the driven roller 7. Since the web 1 is disengaged from the driven roller 7 in practically immediate response to energization of the electromagnet 30, continued rotation of the roller 7 has no bearing on the braking action of the parts 9 and 25. Therefore, the driven roller 7 can be rotated continuously which contributes to uniformity of the transporting action because the motor 6 can operate without any interruptions to drive the roller 7 at a constant speed, also during the intervals when the web 1 is at a standstill. The transmission of signals from the scanning device 2 to the electromagnet 30 can be readily timed in a way to compensate for the minimal delay which is required to complete the braking action so that the web 1 is arrested at the exact moment when the center of a frame line registers with the cutting edge of the knife 5.

The manner in which the scanning device 2 can control the operation of the severing device 4 is disclosed in the copending application Ser. No. 18,904 filed Mar. 12, 1970 by Frankiewicz et al, and owned by the assignee of the present application.

Of course, the improved apparatus can be used for intermittent transport of webs in other types of machines or equipment. For example, and as shown in FIG. 3, the apparatus can be used for intermittent transport of a web 101 in a photographic copying machine wherein successive frames of a photosensitive layer are to be placed into registry with an exposure aperture. FIG. 3 merely shows certain details of the photographic copying machine including an exposing station 34 located to the left of a light-confining duct 35 and in the path of light which is focussed on successive frames by a lens 36. The light which issues from a suitable source (not shown) and passes through a transparency is caused to impinge onto an unexposed frame of the web 101 while the latter is at a standstill. The scanning device 2 of FIG. 1 is replaced by a modified scanning device 37 which includes a metering device acting not unlike a frame counter and serving to produce signals in response to scanning of a predetermined unit lengths of the web 101 to cause the stoppage of the web at the exact moment when an unexposed frame registers with the exposing station 34.

The metering device comprises a small wheel 38 which is biased against the rear (upper) side of the web 101 (i.e., against the side which is not provided with a photosensitive layer) and rotates in response to lengthwise movement of the web in a direction to the right, as viewed in FIG. 3 (see the arrow 33). The wheel 38 is located directly opposite (above) a second wheel 39 which bears against the underside of the web 101. The shaft of the wheel 38 carries a disk 40 with an annulus of perforations or holes 40a. That portion of the disk 40 which is provided with the holes 40a travels across the path of a light beam issuing from a light source (not shown) of a photoelectric detector which further includes a light sensitive element 41. The latter is exposed to light issuing from the light source only when the light beam is free to pass through one of the holes 40a. The light sensitive element 41 then produces an electric impulse which is transmitted to an electronic impulse counter 42. The latter is of known design; its purpose is to count the number of impulses which are transmitted by the light sensitive element 41 and to produce a signal which energizes the electromagnet 30 of the braking device 3 in response to reception of a preselected number of impulses, i.e., in response to transport of a predetermined length of the web 101 through the nip of the wheels 38 and 39. The parts of the transporting and braking devices of the apparatus shown in FIG. 3 are identical with those of the apparatus shown in FIGS. 1 and 2 and are denoted by similar reference characters. The severing device 4 may but need not be omitted, or it may be inactivated if the web which advances beyond the nip between the rollers 7, 9 of the transporting device is not ready for severing.

Since the masses of the wheels 38, 39 and disk 40 are very small, the metering device of the scanning means 37 does not affect the accuracy of the metering action so that the braking device 3 can arrest the web 101 at accurately determined intervals to thus insure that the width of frame lines between successive exposed frames of the web 101 deviates very little or coincides with an optimum width. The biasing means (not shown) which urges the wheels 38, 39 against the respective sides of the web 101 is preferably strong so as to insure that the web 101 cannot slip with reference to such wheels when it is transported by the rollers 7, 9 as well as during braking to and/or during acceleration from zero speed. The apparatus of FIG. 3 shares the aforediscussed advantages of the apparatus of FIGS. 1 and 2, such as accurate reproducibility of the braking action and the generation of highly effective braking action in practically immediate response to a signal from the scanning device 37.

Without further analysis, the foregoing will so fully reveal the-gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by letters Patent is set forth in the appended 1. Apparatus for manipulating webs of sheet material, particularly webs having photosensitive layers, comprising a transporting device including a driven rotary element arranged to engage one side of a web, an idler roller located opposite said driven element and movable to and from an operative position of engagement with the other side of the web which is engaged by said rotary element to thereby effect a positive lengthwise displacement of the web while dwelling in said operative position, means for biasing said idler roller to said operative position with a force which increases with progressing movement of said idler roller from said operative position, and stop means for limiting the extent of movement of said idler roller from said operative position; and a braking device including a braking element located at said one side of the web and displacing means actuatable to perform a predetermined working stroke and to thereby move said braking element into braking engagement with the web and to substantially simultaneously move said idler roller from said operative position against the opposition of said biasing means, said stop means being positioned to arrest said idler roller shortly before said displacing means completes said working stroke.

2. Apparatus for manipulating webs of sheet material, particularly photographic film, comprising a transporting device including a driven roller having a peripheral layer consisting of a'material having a high coefficient of friction and arranged to engage one side of a 'web, said driven roller comprising a pair of axially spaced coaxial portions, drive means having a shaft supportingly connected with and arranged to transmit torque to said portions of said driven roller, and an idler roller located opposite said driven roller and movable to and from an operative position of engagement with the other side of the web which is engaged by said driven roller to positively advance the web lengthwise while dwelling in said operative position; and a braking device including a braking element located at said one side of the web and displacing means actuatable to move said braking element into braking engagement with the web and to simultaneously move said idler roller from said operative position, said displacing means comprising a forked carrier straddling said shaft between said portions of said driven roller and means for moving said carrier from a first to a second position whereby said carrier causes said braking element to engage said one side of the web.

3. Apparatus as defined in claim 2, wherein said means for reciprocating said carrier comprises a rotary electromagnet, a crank arm rotatable by said electromagnet, and a pin-and-slot connection between said crank arm and said carrier.

4. Apparatus as defined in claim 3, wherein saidelectromagnet is energizable to rotate in a first direction and to thereby move said braking element into engagement with said one side of the web by way of said carrier and said crank arm, and wherein said electromagnet normally tends to rotate in a second direction to retract said braking element from said one side of the web, and further comprising means for limiting the extent of rotary movement of said electromagnet in said second direction.

5. Apparatus for manipulating webs of sheet material, particularly photographic film, comprising a transporting device including a driven roller arranged to engage one side of a web and an idler roller located opposite said driven roller and movable to and from an operative position of engagement with the other side of the web which is engaged'by said driven roller to positively advance the web lengthwise while dwelling in said operative position; and a braking device including a braking element located at said one side of the web, said braking element being of substantially cylindrical shape and having an axis which is substantially parallel to the peripheral surface of said driven roller, and displacing means actuatable to move said braking element into braking engagement with the web and to simultaneously move said idler roller from said'operative position, said displacing means comprising resilient supporting means for said braking element andmeans for deforming said supporting means to thereby move said braking element against said one side of the web, said resilient supporting means comprising at least one leaf spring which is deformable to permit the peripheral surface of said braking element to move into linear contact with said one side of the web in response to actuation of said displacing means.

6. Apparatus for manipulating webs of sheet material, particularly photographic film, comprising a transporting device including a driven roller arranged to engage one side of a web and an idler roller locatedopposite said driven roller and movable to and from an operative position of engagement with the other side of the web which is engaged by said driven roller to positively advance the web lengthwise while dwelling in said operative position; and a braking device including a braking element located at said one side of the web, said braking element being of substantially cylindrical shape and having an axis which is substantially parallel to the peripheral surface of said driven roller, and displacing means actuatable to move said braking element into braking engagement with the web and to simultaneously move said idler roller from said operative position, said displacing means comprising resilient supporting means for said braking element and means for deforming said supporting means to thereby move said braking element against said one side of the web, said means for deforming said supporting means comprising a forked carrier provided with a bridge and motion transmitting means arranged to move into mere point contact with said supporting means to thereby move said braking element against said one side of the web.

7. Apparatus as defined in claim 6, wherein said driven roller comprises two coaxial portions which flank said carrier and wherein said supporting means comprises at least one leaf spring, a socket provided on said leaf spring for said braking element, and follower means engaged by said motion transmitting means and arranged to move said socket and said braking element toward said one side of the web in response to displacement of said carrier.

8. Apparatus as defined in claim 7, wherein the line of contact between said peripheral surface of said braking element and said one side of the web in actuated condition of said displacing means is coplanar with the axis of said driven roller, at least when said idler roller is moved by said braking element from said operative position.

9. Apparatus for manipulating webs of sheet material, particularly webs having photosensitive layers, comprising a transporting device including a driven rotary element arranged to engage one side of a web and an idler roller located opposite said driven element and movable to and from an operative position of engagement with the other side of the web which is engaged by said driven element to thereby effect a positive lengthwise displacement of the web along a predetermined path while dwelling in said operative position; and a braking device including a braking element located at said one side of the web and displacing means actuatable to move said braking element into braking engagement with the web and to substantially simultaneously move said idler roller from said operative position, one of said elements having two spaced-apart portions as considered transversely of said path and the other of said elements being located between said spaced-apart portions of said one element.

10. Apparatus as defined in claim 9, further comprising means for biasing said idler roller to said operative position.

11. Apparatus as defined in claim 10, further comprising scanning means arranged to scan the web for the presence of longitudinally spaced indicia thereon and to actuate said displacing means in response to detection of such indicia.

12. Apparatus as defined in claim 11, further comprising a severing device adjacent to the path of movement of the web downstream of said rollers and arranged to sever the web during each interval between successive lengthwise movements thereof.

13. Apparatus as defined in claim 9, further comprising scanning means including metering means operative to generate impulses in response to detection of predetermined lengths of travelling web and means for actuating said displacing means in response to reception of a predetermined number of such impulses.

14. Apparatus as defined in claim 13, wherein said metering means comprises a wheel adjacent to the path of the web and arranged to rotate in response to lengthwise movement of the web and a photoelectric impulse generating device arranged to produce impulses in response to predetermined successive angular displacements of said wheel.

15. Apparatus as defined in claim 14, wherein said photoelectric signal generating device comprises a disk driven by said wheel and having an annulus of holes, a light source positioned at one side of said disk and arranged to emit a beam of light against said disk so that such light passes through successive holes thereof, and a light sensitive element positioned at the other side of the disk in registry with said light source to produce an impulse in response to impingement of the light beam thereagainst when such light beam passes through one of said holes, said means for actuating being arranged to actuate said displacing means in response to reception of a predetermined number of impulses from said light sensitive element.

16. Apparatus as defined in claim 9, wherein said driven roller has a peripheral layer consisting of a material having a high coefficient of friction.

17. Apparatus as defined in claim 9, wherein said braking element consists of a synthetic plastic material having a high coefficient of friction.

18. Apparatus as defined in claim 9, further comprising manually operated means for moving said idler roller from said operative position.

19. Apparatus as defined in claim 18, wherein said idler roller is pivotable to and from said operative position and said manually operated means comprises a rotary eccentric.

20. Apparatus as defined in claim 9, wherein said displacing means is actuatable to move said braking element into substantially linear braking engagement with the web which is engaged by said driven element and wherein the line of contact between said braking element and said one side of the web in actuated condition of said displacing means is coplanar with the axis of said driven element, at least when said idler roller is moved by said braking element from said operative position.

21. Apparatus as defined in claim 9, wherein the mass of said idler roller is a small fraction of the mass of said driven element.

22. Apparatus as defined in claim 9, wherein the mass of said braking element is a sniall fraction of the mass of said driven element.

23. Apparatus as defined in claim 9, wherein said transporting device further comprises means for biasing said idler roller to said operative position with a force which increases with progressing movement of said idler roller from said operative position, and adjustable stop means for limiting the extent of movement of said idler roller from said operative position, said displacing means being arranged to move said idler roller from said operative position against the opposition of said biasing means.

i i i t 

1. Apparatus for manipulating webs of sheet material, particularly webs having photosensitive layers, comprising a transporting device including a driven rotary element arranged to engage one side of a web, an idler roller located opposite said driven element and movable to and from an operative position of engagement with the other side of the web which is engaged by said rotary element to thereby effect a positive lengthwise displacement of the web while dwelling in said operative position, means for biasing said idler roller to said operative position with a force which increases with progressing movement of said idler roller from said operative position, and stop means for limiting the extent of movement of said idler roller from said operative position; and a braking device including a braking element located at said one side of the web and displacing means actuatable to perform a predetermined working stroke and to thereby move said braking element into braking engagement with the web and to substantially simultaneously move said idler roller from said operative position against the opposition of said biasing means, said stop means being positioned to arrest said idler roller shortly before said displacing means completes said working stroke.
 2. Apparatus for manipulating webs of sheet material, particularly photographic film, comprising a transporting device including a driven roller having a peripheral layer consisting of a material having a high coefficient of friction and arranged to engage one side of a web, said driven roller comprising a pair of axially spaced coaxial portions, drive means having a shaft supportingly connected with and arranged to transmit torque to said portions of said driven roller, and an idler roller located opposite said driven roller and movable to and from an operative position of engagement with the other side of the web which is engaged by said driven roller to positively advance the web lengthwise while dwelling in said operative position; and a braking device including a braking element located at said one side of the web and displacing means actuatable to move said braking element into braking engagement with the web and to simultaneously move said idler roller from said operative position, said displacing means comprising a forked carrier straddling said shaft between said portions of said driven roller and means for moving said carrier from a first to a second position whereby said carrier causes said braking element to engage said one side of the web.
 3. Apparatus as defined in claim 2, wherein said means for reciprocating said carrier comprises a rotary electromagnet, a crank arm rotatable by said electromagnet, and a pin-and-slot connection between said crank arm and said carrier.
 4. Apparatus as defined in claim 3, wherein said electromagnet is energizable to rotate in a first direction and to thereby move said braking element into engagement with said one side of the web by way of said carrier and said crank arm, and wherein said electromagnet normally tends to rotate in a second direction to retract said braking element from said one side of the web, and further comprising means for limiting the extent of rotary movement of said electromagnet in said second direction.
 5. Apparatus for manipulating webs of sheet material, particularly photographic film, comprising a transporting device including a driven roller arranged to engage one side of a web and an idler roller located opposite said driven roller and movable to and from an operative position of engagement with the other side of the web which is engaged by said driven roller to positively advance the web lengthwise while dwelling in said operative position; and a braking device including a braking element located at said one side of the web, said braking element being of substantially cylindrical shape and having an axis which is substantially parallel to the peripheral surface of said driven roller, and displacing means actuatable to move said braking element into braking engagement with the web and to simultaneously move said idler roller from said operative position, said displacing means comprising resilient supporting means for said braking element and means for deforming said supporting means to thereby move said braking element against said one side of the web, said resilient supporting means comprising at least one leaf spring which is deformable to permit the peripheral surface of said braking element to move into linear contact with said one side of the web in response to actuation of said displacing means.
 6. Apparatus for manipulating webs of sheet material, particularly photographic film, comprising a transporting device including a driven roller arranged to engage one side of a web and an idler roller located opposite said driven roller And movable to and from an operative position of engagement with the other side of the web which is engaged by said driven roller to positively advance the web lengthwise while dwelling in said operative position; and a braking device including a braking element located at said one side of the web, said braking element being of substantially cylindrical shape and having an axis which is substantially parallel to the peripheral surface of said driven roller, and displacing means actuatable to move said braking element into braking engagement with the web and to simultaneously move said idler roller from said operative position, said displacing means comprising resilient supporting means for said braking element and means for deforming said supporting means to thereby move said braking element against said one side of the web, said means for deforming said supporting means comprising a forked carrier provided with a bridge and motion transmitting means arranged to move into mere point contact with said supporting means to thereby move said braking element against said one side of the web.
 7. Apparatus as defined in claim 6, wherein said driven roller comprises two coaxial portions which flank said carrier and wherein said supporting means comprises at least one leaf spring, a socket provided on said leaf spring for said braking element, and follower means engaged by said motion transmitting means and arranged to move said socket and said braking element toward said one side of the web in response to displacement of said carrier.
 8. Apparatus as defined in claim 7, wherein the line of contact between said peripheral surface of said braking element and said one side of the web in actuated condition of said displacing means is coplanar with the axis of said driven roller, at least when said idler roller is moved by said braking element from said operative position.
 9. Apparatus for manipulating webs of sheet material, particularly webs having photosensitive layers, comprising a transporting device including a driven rotary element arranged to engage one side of a web and an idler roller located opposite said driven element and movable to and from an operative position of engagement with the other side of the web which is engaged by said driven element to thereby effect a positive lengthwise displacement of the web along a predetermined path while dwelling in said operative position; and a braking device including a braking element located at said one side of the web and displacing means actuatable to move said braking element into braking engagement with the web and to substantially simultaneously move said idler roller from said operative position, one of said elements having two spaced-apart portions as considered transversely of said path and the other of said elements being located between said spaced-apart portions of said one element.
 10. Apparatus as defined in claim 9, further comprising means for biasing said idler roller to said operative position.
 11. Apparatus as defined in claim 10, further comprising scanning means arranged to scan the web for the presence of longitudinally spaced indicia thereon and to actuate said displacing means in response to detection of such indicia.
 12. Apparatus as defined in claim 11, further comprising a severing device adjacent to the path of movement of the web downstream of said rollers and arranged to sever the web during each interval between successive lengthwise movements thereof.
 13. Apparatus as defined in claim 9, further comprising scanning means including metering means operative to generate impulses in response to detection of predetermined lengths of travelling web and means for actuating said displacing means in response to reception of a predetermined number of such impulses.
 14. Apparatus as defined in claim 13, wherein said metering means comprises a wheel adjacent to the path of the web and arranged to rotate in response to lengthwise movement of the web and a photoelectric impulse Generating device arranged to produce impulses in response to predetermined successive angular displacements of said wheel.
 15. Apparatus as defined in claim 14, wherein said photoelectric signal generating device comprises a disk driven by said wheel and having an annulus of holes, a light source positioned at one side of said disk and arranged to emit a beam of light against said disk so that such light passes through successive holes thereof, and a light sensitive element positioned at the other side of the disk in registry with said light source to produce an impulse in response to impingement of the light beam thereagainst when such light beam passes through one of said holes, said means for actuating being arranged to actuate said displacing means in response to reception of a predetermined number of impulses from said light sensitive element.
 16. Apparatus as defined in claim 9, wherein said driven roller has a peripheral layer consisting of a material having a high coefficient of friction.
 17. Apparatus as defined in claim 9, wherein said braking element consists of a synthetic plastic material having a high coefficient of friction.
 18. Apparatus as defined in claim 9, further comprising manually operated means for moving said idler roller from said operative position.
 19. Apparatus as defined in claim 18, wherein said idler roller is pivotable to and from said operative position and said manually operated means comprises a rotary eccentric.
 20. Apparatus as defined in claim 9, wherein said displacing means is actuatable to move said braking element into substantially linear braking engagement with the web which is engaged by said driven element and wherein the line of contact between said braking element and said one side of the web in actuated condition of said displacing means is coplanar with the axis of said driven element, at least when said idler roller is moved by said braking element from said operative position.
 21. Apparatus as defined in claim 9, wherein the mass of said idler roller is a small fraction of the mass of said driven element.
 22. Apparatus as defined in claim 9, wherein the mass of said braking element is a small fraction of the mass of said driven element.
 23. Apparatus as defined in claim 9, wherein said transporting device further comprises means for biasing said idler roller to said operative position with a force which increases with progressing movement of said idler roller from said operative position, and adjustable stop means for limiting the extent of movement of said idler roller from said operative position, said displacing means being arranged to move said idler roller from said operative position against the opposition of said biasing means. 